Current Questions & Answers

MEMBER'S QUESTION;

What are the proper containerboard and combined board temperatures as they make their way through the corrugating process?

 

ASKRALPH RESPONDS:

Here is the temperature information that you will need to monitor the process. The absolute temperatures are critical, but so are the differences across the machine.  If the sheets are not “heating up” uniformly then one can experience difference in the combined board tests. You may also want to review the information in the April 19, 2008 edition of OBM.  See page 4.

MEMBER'S QUSTION:

Does a chart exist that graphically displays ECT vs. Mullen with compression (stacking) strength in pounds? Figure a 40 x 18 x 36 box.

ASKRALPH RESPONDS:

 

The dimensions look like a rectangular tube if my L x W x D memory serves me right.  So, we have a corrugated structure that has an outside perimeter of 116 inches.

 

Here is an evaluation, but it may not be all that you want.  Let me know where I need to expand the chart to answer your question(s) more completely. Also, check the combined board calipers for me.

 

Basis Weight Combinations	Combined Caliper	ECT Minimums  or Ranges	Estimated Top-to-Bottom Compression
90-26-90	0.185	64# to 90#	1740 to 2440#
Various	0.170	55# minimum	1433#
69-26-69	0.175	57# to 72#	1507 to 1902#
Various	0.168	44# minimum	1140#
42-26-69	0.165	43# to 60#	1104 to 1539#
Various	0.160	40# minimum	1012#

 

Remember, I did the math without anyone else checking me.  It this is a sustainability issue we did not consider the differences in weights of the corrugated options.

 

 

 

 

M EMBER'S QUESTION:

I need to get some information on starting an ECT degradation study.  To keep this simple at the start we are looking only to study 32 ECT and work off of our flexo and then branch out to other machines and board grades later on.  Here are a couple of questions I hope you can help me with:

We don’t have an internal testing lab.  Who should we be sending the samples to for testing?  Should we be sending the same samples to more than one testing lab?

The main test that needs to be performed is crush, is that correct?  Is it correct to say that one can not know the ECT value of board without crushing it?

Do you have a line on the testing equipment?  I found a ECT crush tester for about $16,000 plus a special cutter for another $2000 as you can’t crush the material at all when you cut it for sampling  because it will skew test results.  Are most people seeing an advantage in internal equipment or are they outsourcing the testing?

Do you have an outline of how we should be going about doing this testing?

I will probably have more questions later but lets start with these for now. Thank you very much.

 

ASKRALPH RESPONDS:

Great questions and ones all independent plants should be asking.

 

First, I’m a great believer in having your suppliers doing this work for you and ultimately them.  They usually have no quantifiable documentation about what they are sending you.  They typically only assume that if they combine certain basis weight board combinations than they are okay.  The AICC Degradation Study blew this mindset out of the water!  And there is a 40% variation between corrugators in their ability to achieve potential ECT and FCT targets from the CD ring crush and concora (flutings) of the components.  If you suppliers choose not to participate in this learning, I will gladly recommend three different labs to you, although I do have a favorite.

Second, you will want to have both Edge Crush and Flat Crush tests conducted.  You may even want to take samples at different crush points through the converting equipment.  It would be best if you started with boxes in strapped bundles, which you break open and select samples, and incoming sheets before converting. I like to also consider pin adhesion strength on the single face and double back sides, but this can wait to later.

Third, testing equipment is not cheap.  Triad Packaging just taken ownership of some equipment from Emerson.  You may want to benchmark you existing situation and then let’s talk again.  I know of very little testing on-going that is outsourced.  At $150/hour it can be expensive.  Keep pushing back on your suppliers.  I can provide all the TAPPI Test Methods and sampling procedures once you embrace the concept of evaluating you incoming sheets and outgoing boxes.  In the Study we found deterioration loss from 0 to 39 percent!

 

 

 

 

MEMBER:  Will you share some of the knowledge you have gained about fluting, corrugating rolls, and the single face operation?  We believe we have developed technological improvements to the design of corrugating rolls which may offer users additional fibre savings and reduced cost.  Please recommend a design experiment so that we may document and quantify these statements.

RALPH YOUNG:  It will be our delight to assist you and others in demonstrating and defining improvements that will benefit the independent members.  If your technology sets a new standard in performance than we want to know.

We discussed the four major fluting properties of caliper, coefficient of friction, MD tensile and MD stretch. When you flute the range of mediums available in the North and Central America, these are four critical properties, along with others, that must be measured to ascertain the ability of your equipment to deliver combined board caliper, flat crush, and edge crush.

Join TAPPI and become a contributing member of the CORBOTEC committee which meets two or three times a years.  These are the experts that have taught me so much over the years and on which I still depend.

Three major documents you may want to acquire and study on this subject are: Single-face Runnability and Bonding by the IPST, Corrugator Bonding by TAPPI, and Corrugated Medium: Its Influence on Box Plant Operations and Combined Board Properties and Packaging Performance.